American Board of Internal Medicine (ABIM) Certification Practice Exam

When should oxygen be administered in the presence of right-sided heart failure?

1. Only for heart rates below 60

2. With a PO2 less than or equal to 55 mm Hg

3. If the patient is experiencing a cough

4. Only in the presence of diabetes

The correct answer is: With a PO2 less than or equal to 55 mm Hg

Administering oxygen during episodes of right-sided heart failure is primarily indicated when there is significant hypoxemia, which is typically defined by a partial pressure of oxygen (PO2) of 55 mm Hg or less. In this context, the oxygen saturation levels are critical, as patients with right-sided heart failure may have impaired gas exchange due to underlying pulmonary issues, such as chronic obstructive pulmonary disease (COPD) or pulmonary hypertension. Low levels of oxygen can exacerbate right-sided heart failure due to increased pulmonary vascular resistance, thereby worsening the overall condition of the patient. Therefore, it is clinically appropriate to provide supplemental oxygen when the PO2 falls to that level, ensuring that the patient maintains adequate oxygenation and minimizing the risk of further cardiac sympathetic response. Other factors such as heart rate, cough, or diabetes do not constitute specific guidelines for oxygen therapy in the context of right-sided heart failure. Heart rate might influence clinical decisions but is not a definitive criterion for oxygen administration. Cough may indicate other clinical issues but does not directly necessitate oxygen therapy. Lastly, the presence of diabetes may complicate the patient’s overall condition but is not a standalone reason for oxygen administration. The key factor remains the oxygenation level as measured by PO2